Method for heating pressing plates of continuous flat press

ABSTRACT

Method for heating pressing plates of a continuous flat press for maintaining surface temperature thereof below 100* C. by utilizing steam. The inside pressure of a conduit disposed in said pressing plate is maintained at a predetermined pressure below an atmospheric pressure while supplying steam into said conduit. And it is preferably applied for carrying out the present method that the partial pressure of air in said conduit is discharged before supplying said steam into said conduit.

United States-Patent Ishizawa et al.

[ 51 Mar. 7, 1972 METHOD FOR HEATING PRESSING PLATES OF CONTINUOUS FLATPRESS Inventors: Kazutomo lsliizawa; Yasunori Nagata;

Junnosuke Abe, all of Osaka; Akira Fuknoka, Tokyo, all of JapanAssignee: Kanegafuchi Boseki Kabushiki Kaisha,

Tokyo, Japan Filed: Dec. 19, 1969 Appl. No.: 886,525

Foreign Application Priority Data Dec. 29, 1968 Japan ..43/96481 US. Cl..l65/l, 165/111, 165/32, 100/93 P Int. Cl ..F28d 7/10 FieldofSearch..l65/l,32,39,111,168,71; 100/93 P [56] References Cited UNITED STATESPATENTS 1,847,573 3/1932 Rupp ..l65/l68 X 3,525,098 8/1970 Vox ..l65/48X Primary Examiner-Frederick L. Matteson Assistant Examiner-W. C.Anderson Attorney-Robert E. Burns and Emmanuel J. Lobato [.57] ABSTRACTMethod for heating pressing plates of a continuous flat press formaintaining surface temperature thereof below 100 C. by utilizing steam.The inside pressure of a conduit disposed in said pressing plate ismaintained'at a predetermined pressure below an atmospheric pressurewhile supplying steam into said conduit. And it is preferably appliedfor carrying out the present method that the partial pressure of air insaid conduit is discharged before supplying said steam into saidconduit.

2 Claims, 2 Drawing Figures PAIENTEDHAR 7 I972 TEMPERATURE OF HOT WATERTEMPERATURE OF PRESSING PLATE OUTLET OF HOT WATER INLET OF HOT WATERATTORNEY METHOD FOR HEATING PRESSING PLATES OF CONTINUOUS FLAT PRESS Thepresent invention relates to an improved. method for heating pressingplates of continuous flat press at a temperature below 100C. byutilizing steam.

Generally, in the finishingprocess of textile fabrics such as worsted orwoolen fabrics, certain union fabrics made. of worsted or woolen yarnor-blended yarn containing thesame synthetic fibers, pressingofthe'fabrics must be appliedfor glazing, providing dimensional stabilityand improving. hand feeling of the fabrics. It is well known that apaper-pressing method has been applied, for the above-mentioned purpose.

The paper-pressingv operation applied to high-quality worsted fabrics isinevitable for attainingvery elegant luster and good hand feeling.However, a fairly long time is required to complete the above-mentionedpaper-pressing operation and moreover, the folds of the fabric are freefrom the paper'- pressing operation. Therefore, in the paper-pressingoperation, it is required to transfer the fabric, which has completed afirst operation, to a lift table and at the same time, the insertion ofthe press papers are required to be changed;

For carrying out the above-mentioned paper-pressing operation in theconventional paper-pressing equipment, a plurality of presses and liftsare required to be. used.

To eliminate the above-mentioned drawbacks involved in.

the paper-pressing method, a now well-known continuousflat press such asHattersley Pickard-Flat Press was developed and these machines are nowbeing practically applied. for the continuous pressing operation. In aunit operation, a fabric is.-

held by a pair of press-plates under heat while one of the pressingplates is pushed to the other pressing plate by;utilizing pneumatic oroil pressure, the fabric just completed in the pressing operation ismoved forward by a predetermined distance while the pressing action bythe two press-platesis.

released. The above-mentioned operations are alternately carried outintermittently. By utilizing the above-mentioned continuous flat press,the pressing operation of the fabric can be carried out speedily andefficiently.

Generally, in the pressing operation of the fabric for providing lusterthereof, pressure, temperature, humidity contained. in thefabric, andoperating time are veryimportant factors to carry out the pressingoperation. In these importantfactors, it is particularly required tocontrol the temperature of the pressing operation. Heating of thepressing plates is carried out by supplying a heating medium into aheating conduit or conduits formed therein. In case the requiredtemperature of the pressing plate is higher than 100 C., steam is usedas the heating medium, while in case. the required temperature is below100 C., hot water is used as the heating medium. However, in the lattercase, the surface temperature of the pressing plate is very difficult tomaintain in a uniform condition, and it.

is required to supply the hot water with a high flow rate for preventingthe irregular distribution of the surface temperature of the pressingplate.

The principal object of the present invention is to provide an improvedheatingmethod of the pressing plates of the continuous flat presswherein the pressing plates are always maintained at a uniformtemperature below l C. with high heating efficiency.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings towhich the scope of the invention is no way limited.

FIG. 1 is an explanatory diagram for illustrating the dropping of thetemperature of the hot water supplied into a conduit formed in apressing plate when the surface temperature of the pressing plate ismaintained at a uniform, constant value,

FIG. 2 is a schematic diagram of a heating device applied to thepressing plate of the continuous flat press, according to the presentinvention.

For better understanding of the present invention, firstly, the drawbackof the heating method applied to the conventional flat press isanalytically illustrated.

Now, aconventionalpressing platemaintaining its temperature at C. bysupplying hot water, is considered. The required quantity of heat formaintaining the pressing plate at 95 C. is supposed to be 7,000KcaL/hour. In the above-mentioned condition, the followingequation isobtained:

Q: quantity of heat required to maintain the temperature of a pressingplate at'95 C.

U: heattransfer coefficient with respect to transmitting heatenergy'from the hot water to the pressing plate made of iron.

A: area of heat transmission of a conduit for flowing the hot water(dia. of the conduit =22 mm.

W: flow rate ofthe circulation of the hot water kg./hr.

C,: specific heat at constant pressure KcaL/kg. C.

A0,: difference between a temperature of the hot-water at an entrance ofthe conduit and that of the pressing plate.

A0 difference between atemperature of the hot water at an outlet oftheconduit and that of the pressing plate.

A0 differencebetween a temperature of the hot water at the inlet of theconduit and that at the outlet of the conduit;

The relation between 0,, 0 and 0;, is shown in FIG. 1. Referring to FIG.1, and assuming that'the differential temperature A0, is 4 C. with the.following measured data: Q=7,000 Kcal./hr., U=340 KcalJ/m. hr. C., andA=l .3 m.; then,

As isclearly understood from the above-mentioned calculation, tomaintain the pressingplate at 95 C. it is necessary to continuouslysupply hot water of l35 C. at a flow rate of 32.1 kg./min. In other.words, the temperature of the hot water supply is about 40 C. higherthan that of the pressing plate, moreover, the flow rate of 32.1 kgJmin.is a distinctly, large quantity of hot water, which is a required supplyfor maintaining the temperature of the pressing plate at 95 C.

In fact, there is a certain limitation for enlarging the area A of theheattransmission of the conduit, because of the construction of thepressing plate.

Therefore, it is required to make A0, as large as possible fortransmitting a sufficient quantity of heat Q from the hot water to thepressing plate. In other words, in the case of heating the pressingplate at 80 C. C. by utilizing hot water in a uniform condition, it isquite certain that a quantity of exchange heat between the hot water inthe conduit and the pressing plate is insufficient for attaining theuniform condition of the pressing plate even though the differencebetween the temperature of the hot water at the inlet of the conduit andthat at the outlet of the conduit is very large.

The principle of the present invention is based upon a fact that it iscapable of heating the pressing plate uniformly by steam, provided thata pressure in the conduit fonned in the pressing plate is properlyadjusted. It is important that the capacity of the heat transmission ofthe steam, in other words, value of U is remarkably larger than that ofthe hot water.

Referring to FIG. 2 showing an embodiment of the device for carrying outthe present invention, steam of comparatively low pressure is suppliedto a heat medium conduit 2 formed in a pressingplate 1 from a steamsupply pipe 3. The steam supplied to the conduit 2 imparts heat to thepressing plate while passing through the conduit 2 so that thetemperature of the pressing plate 1 becomes a predetermined level. Steampressure in the conduit 2 is indicated by a pressure gauge 4. An outletof the conduit 2 is connected to a steam trap 7 through a conduit 14 anda valve 6 mounted on the conduit 14 and further connected to an inlet ofa pump 10 through a valve 8 and a pressure gauge 9. A bypass conduit 11is connected to the conduit 14 as shown in FOG. 2, and a valve 12 ismounted on the bypass conduit 11.

The method for heating the pressingplate of the continuous flat pressutilizing the above-mentioned device ishereinafter illustrated. As afirst step, valves 5 and 6 are closed and the valve 12 is opened. Next,the pump 10 is driven so that the partial pressure of air in the conduit2 is decreased, until the air pressure becomes a predetermined value.Next, the valve 12 is closed and the valve 5 is opened so that steam issupplied into the conduit 2 while the pump is continuously driven andthe valves 6 and 8 are opened. in case the pressing plate 1 is heated ata temperature below 100 C., the inside pressure of the conduit 2 ismaintained at a proper pressure below an atmospheric pressure. Since thesupplied steam is condensed after imparting heat to the pressing plate1, so that a drain liquid is produced inside the conduit 2, it isrequired to control the pressure in the conduit 14, as indicated at thepressure gauge 9 (hereinafter referred to as secondary pressure), sothat the above-mentioned drain liquid can be discharged to the outsideof the device through the steam trap 7. By our experimental tests, itwas found that a primary pressure indicated by the pressure gauge 4should be maintained at a pressure higher than a secondary pressureindicated by the pressure gauge 9 by at least 0.1 kg./cm. preferably 0.3kg./cm. if the above-mentioned pressure difference is below 0.1 kg./cm.it is impossible to discharge the above-mentioned drain and to maintainthe surface temperature of the pressing plate 1 in uniform condition. Itis recommended to use a Nashtype water sealing pump, which is capable ofdischarging the drain, as a decompression pump for carrying out thepresent invention. By utilizing the above-mentioned decompression pump,the remaining partial pressure of air is completely removed during thedischarging operation of the drain through the steam trap 7, even thoughthe partial pressure of air still remains in the conduit 2 aftercompletion of the first operation for decreasing the partial pressure ofair. In the above-mentioned operation, the drain is discharged from thedrain discharging outlet 15, while air or steam is discharged from thedischarging outlet 13.

As mentioned above, in case of carrying out the pressing operation bythe continuous flat press in a temperature condition below 100 C., theheating method of the invention is applied to a decompressionsteam-heating method. in spite of using a long meandering conduit havingsmall cross-sectional diameter, since the conduit is heated uniformly bythe adiabatic compression effect by the supplied steam, the temperaturein the entire conduit within the pressing plate becomes uniform if thepressure in the conduit is maintained in uniform condition. Therefore,the distribution of temperature of the pressing plate becomes veryuniform. Therefore, by applying the above-mentioned heating method,according to the present invention, a long pending problem with respectto the drawback of the conventional flat press, which is illustrated inthe preamble of this specification, can be completely solved.Consequently, a uniform flat-pressing operation can be carried out withhigh efficiency for pressing the high-grade worsted fabrics and variousfabrics which require the operation at a temperature below I00 C., byapplying the heating method of the present invention.

What is claimed is:

1. An improved method of heating a pressing plate of a continuous flatpress provided with at least one conduit formed therein for flowing aheating medium through said flat press, and provided with a steam traphaving an input connected to said conduit, and of maintaining saidpressing plate at a predetermined temperature below C., comprising thesteps of discharging air from said conduit, supplying steam into saidconduit, discharging said steam and drain liquid produced in saidconduit from said conduit through said steam trap while maintaining theinside pressure of said conduit at a predetermined pressure belowatmospheric pressure, and decreasing the pressure at an output of saidsteam trap to a pressure lower than said conduit pressure by at least0.1 kg./cm. thereby maintaining said pressing plate at a uniformpredetermined temperature.

2. An improved heating method as set forth in claim 1, in which saidsteam trap output pressure is decreased to a pressure lower than saidcon duit prssst re by at least 0.3 kg./cm.

1. An improved method of heating a pressing plate of a continuous flatpress provided with at least one conduit formed therein for flowing aheating medium through said flat press, and provided with a steam traphaving an input connected to said conduit, and of maintaining saidpressing plate at a predetermined temperature below 100* C., comprisingthe steps of discharging air from said conduit, supplying steam intosaid conduit, discharging said steam and drain liquid produced in saidconduit from said conduit through said steam trap while maintaining theinside pressure of said conduit at a predetermined pressure belowatmospheric pressure, and decreasing the pressure at an output of saidsteam trap to a pressure lower than said conduit pressure by at least0.1 kg./cm.2, thereby maintaining said pressing plate at a uniformpredetermined temperature.
 2. An improved heating method as set forth inclaim 1, in which said steam trap output pressure is decreased to apressure lower than said conduit pressure by at least 0.3 kg./cm.2.